This invention relates to superconducting magnets and, more particularly, to a superconducting magnet assembly suitable for use as a magnetohydrodynamic generator having a wedge-shaped compressor member end support.
Magnetohydrodynamics (MHD) is a method of generating power by directly converting fuel energy into electrical energy. In a MHD generator, fuel is combusted so as to produce a very high temperature, high pressure ionized gas commonly termed plasma. The plasma generated in the MHD burner is passed through a channel immersed in a high strength magnetic field generated by a plurality of superconducting magnets flanking the channel. The plasma passing therethrough induces an electrical current which is gathered in electrodes lining the channel.
Because of the high efficiency associated with a direct conversion mechanism of MHD, major development efforts are underway to produce commercial scale MHD generators. One problem encountered in designing the commercial MHD generators is providing a superstructure for supporting and enclosing the superconducting magnets which are capable of withstanding the high stresses created when the superconducting magnets are energized.
The superconducting magnet of a MHD generator typically comprises a magnet substructure of a plurality of elongated symmetrical magnet pairs flanking the channel through which the plasma passes. One magnet of each symmetrical pair is disposed on one side of the channel, and its corresponding counterpart is disposed on the other side of the channel. When energized, the magnets want to deform into a circular shape. That is, the long sides of the individual magnets repel each other in inverse proportion to the square of the distance between conductors in which current directions are opposite. Likewise, there is an attraction between conductors in which current directions are in the same direction, causing the pairs of magnets to be attracted in inverse proportion to the square of the distance between conductors. Thus, a conductor forming a magnet if unrestrained will deform into a circle so as to equalize the repulsive and attractive forces on the conductor.
As a result, the superstructure for encircling and supporting the superconducting magnet substructure must effectively absorb and equilibrate the stresses generated when the magnets are energized. An improved superstructure for enclosing and supporting a superconducting magnet assembly which effectively absorbs and equilibrates the repulsive magnetic forces generated within the superconducting magnet assembly is disclosed and claimed in a related application of even date of Shotwell and Gaines entitled, "Superconducting Magnet Assembly".
In accordance with said related application, a magnet substructure is provided for producing the high strength magnetic field within the channel through which the high temperature, high pressure ionized gas is to pass, the magnet substructure having a first magnetic pole disposed above the channel and a second magnetic pole, opposite in polarity to the first magnetic pole, disposed below the channel. The outer surfaces of the first and second magnetic poles are machined to conform to a pre-calculated catenary-shaped curve. A support superstructure for absorbing the equilibrating repulsive magnetic forces generated within the magnet substructure when the first and second magnetic poles are energized completely encloses the magnet substructure. The inner surface of the superstructure is also machined to conform to the pre-calculated catenary-shaped curve so as to mate with the outer surfaces of the first and second magnetic poles. Because of the catenary shape of the interface, the load carried by the support superstructure members will not create a bending moment but will be in pure tension and will efficiently equilibrate the repulsive forces generated within the magnet substructure. The Shotwell and Gaines application does not, however, address the problem of absorbing and equilibrating the attractive magnetic forces generated within the magnet substructure.